The present invention is in the field of antennae and antenna connectors.
This invention relates to an antenna connecting apparatus useful in the automotive industry. More specifically, this invention relates to connecting an on-glass antenna to a transmission cable useful in automotive audio and communication devices.
One difficulty in utilizing on-glass antennae is obtaining a convenient method for connecting a printed on-glass metallic pattern to a transmission cable while providing wide band impedance matching. The impedance matching must be done in the FM frequency band, where the coaxial cable impedance is often 50 ohms, and the much lower AM frequency band, where the antenna and the receiver input impedance is closer to 6,000 ohms.
The present invention is based on a transformer design. The purpose of the transformer is to obtain the proper impedance matching at the FM frequency band from 88 to 108 MHz. A capacitor may also be used if the printed grounding pattern does not contain the proper capacitance. This capacitor behaves like a short circuit in the FM frequency band, and an open circuit in the AM frequency band. The combination results in a wide bandwidth and a transformation from the coaxial cable impedance to the antenna impedance. A convenient method of attachment is also provided for in the current invention.
Although described with respect to the fields of automotive audio and communication devices, it will be appreciated that similar advantages of a convenient wide band antenna connector may obtain in other applications of the present invention. Such advantages may become apparent to one of ordinary skill in the art in light of the present disclosure or through practice of the invention.
The present invention includes antenna connectors, antenna connecting devices, and antenna connecting systems. This invention also includes machines or electronic devices using these aspects of the invention. The present invention may also be used to upgrade, repair or retrofit existing machines or electronic devices or instruments of these types, using methods and components used in the art.
In broadest terms, the antenna connector for providing impedance matching to an electronic device, adapted to receive signals from the antenna, comprises: (1) an insulating substrate containing a mounting element attached to the surface of the substrate, (2) an antenna printed on the insulating substrate, (3) a transmission line adapted to carry a signal from the antenna to the electronic device, (4) a grounding contact adapted to provide an electrical ground for the antenna connector, and (5) a transformer adapted to obtain impedance matching between the transmission line and the antenna, where the poles of one coil of the transformer are connected to the transmission line and to the grounding contact, and the poles of the other coil are connected to the antenna and the grounding contact.
The antenna connector may also contain a capacitor device in connection with the transformer and grounding contact. The capacitor device can be in the form of a conductive pattern, e.g., a conductive mesh pattern, printed on the insulating substrate, in connection with the transformer, that provides a capacitive ground contact. A layer of insulating material can additionally be placed between the conductive pattern and ground. The transmission line will commonly be a coaxial cable, although other methods of transmission may be used. The transmission line is attached to the coil device by a push-on connector, such as a spade lug.
The transformer can alternatively be replaced by a tapped-coil transformer. The tapped-coil transformer should be adapted to obtain proper impedance matching between the transmission line and the antenna, where the poles of the coil are connected to the transmission line and the grounding contact. The antenna is then connected by a tap to the coil device. Changing the location of the tap can permit impedance adjustment.
The present invention also includes an on-glass antenna connector. In broadest terms, the on-glass antenna connector for providing impedance matching to an electronic device, adapted to receive signals from the antenna, comprises: (1) an automotive windshield containing a mounting pad attached to the windshield, (2) an antenna printed on the automotive windshield, (3) a transmission line capable of carrying a signal from the antenna to the electronic device, (4) a grounding contact adapted to provide an electrical ground for the antenna connector, (5) a transformer adapted to obtain impedance matching between the transmission line and the antenna, wherein the poles of one transformer coil are connected to the transmission line and to the grounding contact, and the poles of the other coil are connected to the antenna and the grounding contact, and (6) an insulating substrate, such as a clip, adapted to house the transformer and attach to the mounting pad.
The on-glass antenna connector may also contain a capacitor device in connection with the transformer and the grounding contact. The capacitor device can be in the form of a conductive pattern printed on the glass, in connection with the transformer, that provides a capacitive ground contact. A layer of insulating material can additionally be placed between the conductive pattern and ground. The transmission line will commonly be a coaxial cable, although other methods of transmission may be used. The transmission line is attached to the coil device by a push-on connector, such as a spade lug.
The transformer can alternatively be replaced by a tapped-coil transformer. The tapped-coil transformer should be adapted to obtain proper impedance matching between the transmission line and the on-glass antenna, where the poles of the coil are connected to the transmission line and the grounding contact. The antenna is then connected by a tap to the coil of the transformer. Changing the location of the tap can permit impedance adjustment. It is also recognized that the connector and antenna can be used on any insulating surface of a vehicle.